AES and 3-DES Encryption Support for SNMP Version 3

First Published: May 2005

Last Updated: November 8, 2010

The AES and 3-DES Encryption Support for SNMP Version 3 feature enhances the encryption capabilities of SNMP version 3. Data Encryption Standard (DES) support was introduced in Cisco IOS Release 12.0 and expanded in Cisco IOS Release 12.1. This support for Simple Network Management Protocol (SNMP) version 3 User-Based Security Model (USM) is complaint with RFC 3414, which defines DES as the only required method of message encryption for SNMP version 3 authPriv mode.

The AES and 3-DES Encryption Support for SNMP Version 3 feature adds Advanced Encryption Standard (AES) 128-bit encryption in compliance with RFC 3826. RFC 3826 extensions have been included in the SNMP-USM-AES-MIB. In addition, Cisco-specific extensions to support Triple-Data Encryption Algorithm (3-DES) and AES 192-bit and 256-bit encryption have been added to the CISCO-SNMP-USM-MIB. Additional information can be found in the Internet-Draft titled Extension to the User-Based Security Model (USM) to Support Triple-DES EDE in "Outside" CBC Mode, which can be found at the following URL: http://www.snmp.com/eso/draft-reeder-snmpv3-usm-3desede-00.txt.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn.An account on Cisco.com is not required.

Information About AES and 3-DES Encryption Support for SNMP Version 3

SNMP Architecture

The architecture for describing Internet Management Frameworks contained in RFC 3411 describes the SNMP engine as composed of the following components:

•Dispatcher

•Message Processing Subsystem

•Security Subsystem

•Access Control Subsystem

Applications make use of the services of these subsystems. It is important to understand the SNMP architecture and the terminology of the architecture to understand where the Security Model fits into the architecture and interacts with the other subsystems within the architecture. The information is contained in RFC 3411 and your are encouraged to review this RFC to obtain an understanding of the SNMP architecture and subsystem interactions.

Encryption Key Support

In the AES and 3-DES Encryption Support for SNMP Version 3 feature the Cipher Block Chaining/Data Encryption Standard (CBC-DES) is the privacy protocol. Originally only DES was supported (as per RFC 3414). This feature adds support for AES-128 (as per RFC 3826) and AES-192, AES-256 and 3-DES (as per CISCO-SNMP-USM-OIDS-MIB).

The AES Cipher Algorithm in the SNMP User-based Security Model draft describes the use of AES with 128-bit key size. However, the other options are also implemented with the extension to use the USM. There is currently no standard for generating localized keys for 192- or 256-bit size keys for AES or for 168-bit size key for 3-DES. There is no authentication protocol available with longer keys.

Management Information Base Support

The AES and 3-DES Encryption Support for SNMP Version 3 feature supports the selection of privacy protocols through the CLI and the Management Information Base (MIB). A new standard MIB, SNMP-USM-AES-MIB, provides support for the 128-bit key in AES. The extended options of AES with 192- or 256-bit keys and 3-DES are supported as extensions to the SNMP-USM-MIB, in the Cisco-specific MIB, CISCO-SNMP-USM-EXT-MIB.

Adds an SNMP user, specifies a group to which the user belongs, specifies the authorization algorithm to be used (MD5 or SHA), specifies the privacy algorithm to be used (DES, 3-DES, AES, AES-192, or AES-256), and specifies the password to be associated with this privacy protocol.

Verifying SNMP User Configuration

To display information about the configured characteristics of Simple Network Management Protocol (SNMP) users, use the show snmp user command in privileged EXEC mode.

SUMMARY STEPS

1. enable

2. show snmp user [username]

Note The show snmp user command displays all the users configured on the router. However, unlike other SNMP configurations, the snmp-server user command will not appear on the "show running" output.

DETAILED STEPS

Step 1 enable

Enters privileged EXEC mode. Enter your password when prompted.

Step 2 show snmp user [username]

The following example specifies the username as abcd, the engine ID string as 00000009020000000C025808, and the storage type as nonvolatile:

Technical Assistance

Description

Link

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Feature Information for AES and 3-DES Encryption Support for SNMP Version 3

Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Note Table 1 lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Table 1 Feature Information for AES and 3-DES Encryption Support for SNMP Version 3

Feature Name

Releases

Feature Information

AES and 3-DES Encryption Support for SNMP Version 3

12.2(33)SRB12.2(33)SB12.2(33)SXI12.4(2)T15.0(1)SCisco IOS XE 3.1.0SG

The AES and 3-DES Encryption Support for SNMP Version 3 feature enhances the encryption capabilities of SNMP version 3. DES support was introduced in Cisco IOS Release 12.0 and expanded in Cisco IOS Release 12.1. This support for SNMP version 3 USM is complaint with RFC 3414, which defines DES as the only required method of message encryption for SNMP version 3 authPriv mode.

The AES and 3-DES Encryption Support for SNMP Version 3 feature adds AES 128-bit encryption in compliance with RFC 3826.

AES and 3-DES Encryption Support for SNMP Version 3 was introduced in Cisco IOS Release 12.4(2)T.

AES and 3-DES Encryption Support for SNMP Version 3 was integrated into Cisco IOS Release 12.2(33)SRB.

AES and 3-DES Encryption Support for SNMP Version 3 was integrated into Cisco IOS Release 12.2(33)SB.

This feature was integrated into Cisco IOS Release 15.0(1)S.

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